Journal article
Examination of the selective pressures on a live PRRS vaccine virus
Stald/vægterservice, Division of Virology, National Veterinary Institute, Technical University of Denmark1
Division of Virology, National Veterinary Institute, Technical University of Denmark2
National Veterinary Institute, Technical University of Denmark3
Technical University of Denmark4
Sektion for Eksotiske Virussygdomme, Division of Virology, National Veterinary Institute, Technical University of Denmark5
We determined the ORF5 and 7 sequences of 20 pathogenic revertants of a live PRRSV vaccine. The sequence analysis confirmed all 20 isolates to be of vaccine origin. Having established that clonal introduction of American (vaccine) PRRS virus had occurred in Denmark, we could perform analysis of the selective pressure this attenuated virus had experienced during reversion.
An analysis of nucleotide mutations showed a similar rate of mutations in the two genes (ORF5 and 7). However, non-synonymous mutations in ORF7 were eliminated by purifying selection. In contrast, non-synonymous mutations in ORF5 were tolerated or even selected for. The cDNA sequencing of the 20 vaccine virus revertants identified two single nucleotide mutations located in ORF5 and in ORF6 that we suggest are involved or at least linked to the attenuation of the vaccine virus and to the subsequent reversion to virulence.
Language: | English |
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Publisher: | Springer-Verlag |
Year: | 1999 |
Pages: | 2389-2401 |
ISSN: | 14328798 and 03048608 |
Types: | Journal article |
DOI: | 10.1007/s007050050652 |
Amino Acid Sequence Animals Base Sequence Biomedicine DNA, Complementary Infectious Diseases Medical Microbiology Molecular Sequence Data Mutation Open Reading Frames Porcine Reproductive and Respiratory Syndrome Porcine respiratory and reproductive syndrome virus Reverse Transcriptase Polymerase Chain Reaction Selection, Genetic Sequence Alignment Sequence Analysis, DNA Swine Swine Diseases Vaccines, Attenuated Viral Vaccines Virology Virulence